I’d like to say this has a happy ending but this morning the repeats stopped working again. I power cycled the hub in the hopes that would resolve it but it hasn’t. I haven’t made any configuration changes since I recreated the activities. Things ran fine for a couple of days and then stopped working for repeats.

I recreated the activities and now the repeats are happening. It isn't clear what's different between the activities. I created them the same way (so far as I can tell) but the new ones work and the old ones don't.

To clarify my last statement, when I said "using the device directly" I meant using the X1 in device mode instead of activity mode.

It doesn’t seem device specific, but it is with an Apple TV 4K and nVidia Shield Pro (both being controlled by Bluetooth) and a Sony HT-A7000 soundbar controlled with IR. Repeats work when using the device directly but when in activity mode key repeats don’t happen.